Dual base stations for wireless communication systems

ABSTRACT

A network apparatus comprises a controller to determine a first base station for transmitting data and to determine a second different base station for receiving data. In one embodiment, the network apparatus further comprises a transceiver to transmit data to the first base station while associated with the second base station. The transceiver is operable to receive data from the second base station while associated with the first base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/142,582, filed on Jan. 5, 2009, entitled “Advanced WirelessCommunication Systems and Techniques”, and the contents of whichincorporated herein by reference as if set forth herein in full.

TECHNICAL FIELD

Embodiments of the invention relate to data communication; moreparticularly, embodiments of the invention relates to managingconnections to base stations.

BACKGROUND

It is becoming increasingly common to find broadband wireless networkingcapabilities (e.g., IEEE 802.11, 802.16e, etc.) in mobile devices. Inmany network environments, a network device establishes communicationwith an access point, e.g., a base station of a cellular network, forboth uplink and downlink access.

Wireless communication interfaces may use up a large portion of totalpower supply available to mobile devices operating on batteries. Powermanagement schemes are used in conjunction with network devices toextend the battery lifetime of mobile communication devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be understood more fully fromthe detailed description given below and from the accompanying drawingsof various embodiments of the invention, which, however, should not betaken to limit the invention to the specific embodiments, but are forexplanation and understanding only.

FIG. 1 is a block diagram showing dual base stations system inaccordance with one embodiment of the invention.

FIG. 2 shows a block diagram of a network apparatus in accordance withone embodiment of the invention.

FIG. 3 is a block diagram showing costs of connectivity of acommunication system in accordance with one embodiment of the invention.

FIG. 4 a shows an embodiment of a system communicating control datawithout using a backbone connection.

FIG. 4 b is an embodiment of a system communicating control data withthe use of a backbone connection.

FIG. 5 is a flow diagram of one embodiment of a process to determine abase station for an uplink transmission and a base station for adownlink transmission.

FIG. 6 is a diagram representation of a wireless communication system inaccordance with one embodiment of the invention.

FIG. 7 illustrates a computer system for use with one embodiment of thepresent invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providea more thorough explanation of embodiments of the present invention. Itwill be apparent, however, to one skilled in the art, that embodimentsof the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form, rather than in detail, in order to avoidobscuring embodiments of the present invention.

Some portions of the detailed descriptions which follow are presented interms of algorithms and symbolic representations of operations on databits within a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the following discussion,it is appreciated that throughout the description, discussions utilizingterms such as “processing” or “computing” or “calculating” or“determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical(electronic) quantities within the computer system's registers andmemories into other data similarly represented as physical quantitieswithin the computer system memories or registers or other suchinformation storage, transmission or display devices.

Embodiments of present invention also relate to apparatuses forperforming the operations herein. Some apparatuses may be speciallyconstructed for the required purposes, or it may comprise a generalpurpose computer selectively activated or reconfigured by a computerprogram stored in the computer. Such a computer program may be stored ina computer readable storage medium, such as, but not limited to, anytype of disk including floppy disks, optical disks, CD-ROMs, DVD-ROMs,and magnetic-optical disks, read-only memories (ROMs), random accessmemories (RAMs), EPROMs, EEPROMs, NVRAMs, magnetic or optical cards, orany type of media suitable for storing electronic instructions, and eachcoupled to a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the required method steps. The required structurefor a variety of these systems will appear from the description below.In addition, embodiments of the present invention are not described withreference to any particular programming language. It will be appreciatedthat a variety of programming languages may be used to implement theteachings of the invention as described herein.

A machine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes read onlymemory (“ROM”); random access memory (“RAM”); magnetic disk storagemedia; optical storage media; flash memory devices; etc.

The method and apparatus described herein are for determining basestations for wireless network transmissions. Specifically, determining abase station for transmitting data (uplink) based on distances of basestations is primarily discussed in reference to mobile devices. However,the methods and apparatus for determining a base station for an uplinktransmission based on distances of base stations is not so limited, asit may be implemented on or in association with any integrated circuitdevice or system, such as cell phones, personal digital assistants,embedded controllers, mobile platforms, desktop platforms, and serverplatforms, as well as in conjunction with other resources, such ashardware/software threads.

The following inventive embodiments may be used in a variety ofapplications including transmitters and receivers of a radio system.Radio systems specifically included within the scope of the presentinvention include, but are not limited to, network interface cards(NICs), network adaptors, mobile stations, base stations, access points(APs), hybrid coordinators (HCs), gateways, bridges, hubs, routers,relay stations, repeaters, analog repeaters, and amplify and forwardrepeaters. Further, the radio systems within the scope of the inventionmay include cellular radio telephone systems, satellite systems,personal communication systems (PCS), two-way radio systems, and two-waypagers as well as computing devices including radio systems such aspersonal computers (PCs) and related peripherals, personal digitalassistants (PDAs), personal computing accessories, and all existing andfuture arising systems which may be related in nature and to which theprinciples of the inventive embodiments could be suitably applied.

While the following detailed description may describe exampleembodiments of the present invention in relation to wirelessmetropolitan area networks (WMANs) or other wireless wide area networks(WWANs), the embodiments are not limited thereto and can be applied toother types of wireless networks where similar advantages may beobtained. Such networks for which inventive embodiments may beapplicable specifically include, wireless personal area networks(WPANs), wireless local area networks (WLANs), WWANs such as cellularnetworks, or combinations of any of these networks. Further, inventiveembodiments may be discussed in reference to wireless networks utilizingOrthogonal Frequency Division Multiplexing (OFDM) modulation. However,the embodiments of present invention are not limited thereto and, forexample, the embodiments can be implemented using other modulation orcoding schemes where suitably applicable.

Overview

FIG. 1 is a block diagram showing dual base stations system inaccordance with one embodiment of the invention. In one embodiment, anetwork apparatus associates with two different base stations for uplink(transmitting data from the apparatus) and downlink transmissions(receiving data by the apparatus) to improve downlink capacity and toreduce uplink transmit power of the network apparatus.

Referring to FIG. 1, in one embodiment, communication network 100comprises relay station 130, base station 140, mobile stations 104-106,and networks 112. In one embodiment, boundary 120 and boundary 122logically splits coverage area of mobile station 104 into 3 zones (zoneA 150, zone B 151, and zone C 152).

It will be appreciated by those of ordinary skill that FIG. 1 is alinear model of communication network 100. The coverage area is shown asdivided linearly by boundaries 120 and 122 which are not necessarilylinear in an actual network. For example, in some embodiments, boundary120 forms a part of a network cell boundary. In one embodiment, boundary122 is a locus of points approximately equidistant from relay station130 and base station 140. Boundary 120 is a locus of points withapproximately equal downlink signal strength values (or receive powervalues) at the mobile station 104 with respect to receiving data fromrelay station 130 and from base station 140. Zones (zones 150-152) andboundaries (e.g., boundaries 120 and 122) are shown in block diagramform, rather than in detail, in order to avoid obscuring embodiments ofthe present invention.

In one embodiment, base station 140 is an access point. In oneembodiment, base station 140 performs association authentication andtime/frequency resource allocation. In one embodiment, base station 140is either main, relay, or remote base station. A main base station isconnected with the wired Ethernet. A relay base station relays databetween remote base stations, wireless clients, or other relay stationsto a base station. A remote base station accepts connections fromwireless clients and passes the clients to relay or main stations.

In one embodiment, relay station 130 amplifies and forwardscommunications from mobile station 104 to network 112. In oneembodiment, relay station 130 has capabilities similar to base station140. In one embodiment, relay station 130 acts a base station to providebackward-compatible functionalities to legacy subscriber stations. Inthis case, backhaul link(s) between base station 140 and relay station130 is concealed from legacy subscriber stations. In one embodiment,relay station 130 is a base station similar to base station 140. In oneembodiment, relay station 130 is not connected directly to a corenetwork (e.g., 112) by electrical or wires or optical cables but ratherare connected to the core network via a wireless backhaul (not shown) tobase station 140. In one embodiment, relay station 130 is referred to asa “micro” or “pico” base station.

In one embodiment, mobiles stations 104-106 are also known as subscriberstations. In one embodiment, mobile stations 104-106 include anycombination of stationary devices, mobile devices, and portable wirelesscommunication devices, such as, for example, personal digital assistants(PDAs), laptops or portable computers with wireless communicationcapability, web tablets, wireless telephones, wireless headsets, pagers,instant messaging devices, digital cameras, televisions, medical devices(e.g., a heart rate monitor, a blood pressure monitor, etc.), or otherdevices that communicate information wirelessly.

In one embodiment, base station 140 communicates, using radio-frequency(RF) signals, with mobile stations 104-106 allowing mobile stations104-106 to communicate amongst each other as well as allowing mobilestations 104-106 to communicate with external networks 112 (e.g., theInternet).

In one embodiment, mobile station 104 is a standard range mobilestation. In one embodiment, mobile station 106 is an extended rangemobile station. An extended range encompasses a much larger geographicarea than the standard range. In one embodiment, a standard rangeextends up to a couple hundred meters in an unobstructed environment(e.g., outdoors) from base station 140 while the extended range extendsup to a thousand or more meters in an unobstructed environment from basestation 140. In one embodiment, values of transmit power and antennaheights of wireless transceivers in relay stations 130 are less thanthose of base stations 140, whereas those of mobile stations 104 areeven less.

In one embodiment, in conjunction with heterogeneous overlay networkdeployment, mobile station 104 uses two different base stations (e.g.,base station 140, relay station 130) for downlink and uplinktransmissions. In one embodiment, rather than selecting one access pointonly based on signal to interference/noise ratio (SINR) at the mobilestation 104, mobile station 104 associates with two different accesspoints for uplink and downlink transmissions to improve the downlinkcapacity and to reduce the uplink transmit power of mobile station 104.In one embodiment, SINR at the mobile station 104 is measured withrespect to downlink reference signals (e.g., preamble and pilot).

In one embodiment, mobile station 104 selects the two access pointsbased on two criteria. In one embodiment, a first criterion is based ona value indicative of maximum downlink SINR (maxSINR) of signal receivedat mobile station 104. A higher downlink maxSINR results in a higherdownlink capacity (to mobile station 104). In one embodiment, a secondcriterion is based on minimum uplink transmit power at the mobilestation 104 for an uplink transmission (from mobile station 104). In oneembodiment, a minimum uplink transmit power is referred to as a requiredtransmission power. A lower uplink transmit power consumption extendsbattery lifetime of mobile station 104. In one embodiment, mobilestation 104 selects a downlink transmission based on the first criterionand selects an uplink transmission based on the second criterion.

In one embodiment, if base stations 130 and 140 are similar in antennaconfiguration, channels from mobile station 104 to these two basestations show similar scaling properties (for example, channel gainchanges in the distance from a base station) such that selecting aminimum uplink transmission power is approximated by selecting a basestation with the closest distance. In one embodiment, if the aboveconditions do not hold, the uplink transmission power is affected byfactors including distances, the configuration of an antenna, etc.

In one embodiment, a minimal uplink transmission power is estimated byconsidering the ratio of a downlink reference signal's receive power(e.g. SINR) at mobile station 104 versus a known transmission power (forexample, from base station broadcast), assuming that uplink/downlinkchannels are symmetry in terms of channel gains. In one embodiment,mobile station 104 performs explicit signaling with any target basestation to obtain necessary information related to uplink transmissionpower. The following examples related to “closest distance” aredescribed by way of illustration and is in no way intended to beconsidered limiting.

In one embodiment, SINR is defined as signal power divided by a sum ofinterference power and noise power, wherein signal power is a product oftransmission power and channel gain. In one embodiment, a transmissioncapacity is an upper bound on the amount of information that is reliablytransmitted over a communication connection (in terms of bit persecond). In one embodiment, a transmission capacity of a connection isapproximately equal to a value of bandwidth multiplied by log(1+SINR).In one embodiment, a higher SINR results in a higher transmissioncapacity as explained above. In one embodiment, a higher transmissionpower results in a higher SINR and therefore higher transmissioncapacity.

In one embodiment, if downlink and uplink transmissions (also referredto as channels, connections, etc.) are symmetric and all base stations(access points) use a same transmit power value, selecting a basestation based on either a downlink maxSINR value or a minimum uplinktransmit power value yields to the same base station. In one embodiment,if base stations operate on different values of transmit power (in aheterogeneous network, e.g., IEEE 802.16m network), mobile station 104will associate with two different base stations (one for uplinktransmission and one for downlink transmission) when mobile station 104operates in a dual access point zone (DAZ). In one embodiment, transmitpower of a base station 140 is 46 dBm, whereas, transmit power of relaystation 130 is 36 dBm in accordance with an 802.16m network.

In one embodiment, the transmit power of relay station 130 is lower thanthe transmit power of base station 140. Referring to the example shownin FIG. 1, cell boundary 120 is closer to relay station 130 because cellboundary 120 is selected based on maximum received SINR values ofdifferent base stations measured with respect to mobile station 104. Onthe other hand, if mobile station 104 selects a base station based onminimum transmit power, mobile station 104 selects a closer base station(in terms of distance) such that the cell boundary is at the middle (asindicated by boundary 122).

In one embodiment, cell boundary 120 is referred to herein as a downlinkcell boundary. In one embodiment, cell boundary 122 is referred toherein as an uplink cell boundary.

In one embodiment, mobile station 104 associates with the same basestation (i.e., relay station 130) for uplink and downlink transmissionswhile mobile station 104 is located in zone A 150. In one embodiment,mobile station 104 associates with the same base station (i.e., basestation 140) for uplink and downlink transmissions while mobile station104 is located in zone C 152. In one embodiment, mobile station 104associates with the two base stations (i.e., relay station 130 for anuplink transmission and base station 140 for a downlink transmission)while mobile station 104 is located in zone B 151. In one embodiment,zone B 151 is also referred to herein as a dual AP zone (DAZ), wheremobile station 104 associates with two different access points.

In one embodiment, if the cell coverage of base station 140 and relaystation 130 is determined based on a downlink perspective only (i.e.,maximum received SINR at the mobile station 104), mobile station 104selects a base station with a better downlink transmission capacity. Theselected base station however may not be a better base station foruplink transmission if the distance of the base station from mobilestation 104 is greater and mobile station 104 needs to use high transmitpower to establish a uplink connection to the base station.

In one embodiment, a significant gain on system capacity and powersaving at mobile station 104 are observed if mobile station 104 is ableto use different base stations when operating in DAZ. In one embodiment,if the difference of transmit power of base station 140 and relaystation 130 is 10 dB, mobile station 104 is able to save upto 70% ofuplink transmit power on average, if compared to performing bothdownlink/uplink communications with base station 140.

Communication Systems

In one embodiment, base station 140 is a Wireless Fidelity (WiFi) accesspoint. In one embodiment, base station 140 operates in accordance withone or more of the Institute of Electrical and Electronic Engineers(IEEE) 802.11 standards (e.g., IEEE 802.11(a), 802.11(b), 802.11(g),802.11(h), and 802.11(n)), variations, or evolutions thereof.

In one embodiment, communication network 100 is a broadband wirelessaccess (BWA) network and base station 140 is a WorldwideInteroperability for Microwave Access (WiMax) base station or otherbroadband communication station. In one embodiment, base station 140operates in accordance with one or more of the Institute of Electricaland Electronic Engineers (IEEE) 802.16 standards, variations, orevolutions thereof.

In one embodiment, communication network 100 is a wireless local areanetwork (WLAN). In one embodiment, wireless communication network 100 isa wireless personal area network (WPAN), a wireless metropolitan areanetwork (WMAN), a wireless wide area network (WWAN), 3GPP2, 3G LTE, or4G network. In one embodiment, mobile stations 104-106 operate in acarrier sense multiple access (CSMA) mode.

In one embodiment, base station 140 communicates with mobile stations104-106 using spread-spectrum signals within one or more frequencyspectrums. In other embodiments, base station 140 communicates usingorthogonal frequency division multiplexed (OFDM) communication signalswithin one or more frequency spectrums. In one embodiment, base station140 communicates with mobile stations 104-106 selectively using eitherspread-spectrum signals or OFDM communication signals. The OFDM signalscomprise a plurality of orthogonal subcarriers.

In one embodiment, the frequency spectrums used by base station 140comprise either a 5 GHz frequency spectrum or a 2.4 GHz frequencyspectrum. In one embodiment, 5 GHz frequency spectrum includesfrequencies ranging from approximately 4.9 to 5.9 GHz, and 2.4 GHzspectrum includes frequencies ranging from approximately 2.3 to 2.5 GHz,although the scope of the invention is not limited in this respect, asother frequency spectrums are also equally suitable. In some BWA networkembodiments, the frequency spectrum for communications comprisesfrequencies between 2 and 11 GHz, although the scope of the invention isnot limited in this respect.

In one embodiment, antennas of base station 140 and antennas of mobilestations 104-106 comprise one or more directional or omnidirectionalantennas including for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas, or other types ofantennas suitable for transmission of RF signals. In one embodiment,base station 140, and mobile stations 104-106 use two or more antennaseach. In one embodiment, instead of the two or more antennas, a singleantenna with multiple apertures is used.

FIG. 2 shows a block diagram of a network apparatus in accordance withone embodiment of the invention. Many related components such as databuses and peripherals have not been shown to avoid obscuring theinvention. Referring to FIG. 2, in one embodiment, network apparatus 260comprises controller 261, transceiver 262, memory 265, and selectionlogic 263. In one embodiment, network apparatus 260 communicates withbase station 270 and base station 271.

In one embodiment, controller 261 monitors network parameters, such as,for example: SINR values with respect to different transmissions (ofdifferent base stations), approximate distances from base stations (forexample via average path loss calculation), transmit power, andcapacities of connections. In one embodiment, controller 261 controlsoperations of network apparatus 260. In one embodiment, memory 265stores programs to be executed by controller 261.

In one embodiment, transceiver 262 includes physical (PHY) layercircuitry for communicating with the physical mediums (wireless orotherwise), media access control (MAC) layer circuitry, and higher-levellayer (HLL) circuitry. In one embodiment, PHY layer circuitry, MAC layercircuitry, and HLL circuitry comprise functionality for both receiverand transmitter operations and include processing circuitry to evaluatecommunications from network apparatus 260, among other things. In oneembodiment, transceiver 262 is connected to a core network, such as anInternet protocol (IP) network, via a wireless connection, a physicalwired connection (e.g., electrical or fiber optic connection), or both.

In one embodiment, selection logic 263 selects base stations (e.g., basestations 270-271) based on two criteria. In one embodiment, a firstcriterion is based on a value indicative of maximum SINR (maxSINR) ofsignal received (e.g., downlink reference signal). A second criterion isbased on minimum transmit power for an uplink transmission from networkapparatus 260. In one embodiment, selection logic 263 selects a downlinktransmission (to network apparatus 260) based on the first criterion andselects an uplink transmission based on the second criterion.

In one embodiment, network apparatus 260 comprises, for example, clientdevices and network points of attachments. In one embodiment, networkapparatus 260 is fixed, stationary, or mobile depending on theparticular environment or implementation and communicates over themedium of free space generally referred to as the “air interface” (e.g.,wireless shared media).

In one embodiment, network apparatus 260 comprises wireless devices thatcomply with or operate in accordance with one or more protocols, suchas, for example, WiFi, Bluetooth, UWB, WiMAX, and cellular protocols.Network apparatus 260 comprises, but is not necessarily limited to, acomputer, server, workstation, laptop, ultra-laptop, handheld computer,telephone, cellular telephone, personal digital assistant (PDA), router,switch, bridge, hub, gateway, wireless device, multi-network, multipleintegrated radio devices, mixed-network device supporting multipleconcurrent radios, WiFi plus cellular telephone, portable digital musicplayer, pager, two-way pager, mobile subscriber station, printer,camera, enhanced video and voice device, and any other one-way ortwo-way device capable of communicating with other devices or basestations. The embodiments are not limited in this context.

FIG. 3 is a block diagram showing costs of connectivity of acommunication system in accordance with one embodiment of the invention.Referring to FIG. 3, a communication system comprises base station 310,mobile station 330, and relay station 320. It will be appreciated bythose of ordinary skill that other relay stations and base stations thatpresent in the communication system are not shown to avoid obscuringembodiments of the present invention.

In a network that supports dual AP zone (DAZ), costs induced fromadditional hops via relay stations (e.g., 343) are determined with oneof the following methods. In one embodiment, mobile station 330 selectsto use a connection to base station 310 rather than a connection viarelay station 320 to avoid the additional relay cost.

In one embodiment, a relay network is based on IEEE 802.16m where thedelay of wireless backhaul connection (backbone connection) between basestation 310 and relay station 320 is small and predictable. In addition,MAC coordination between base station 310 and relay station 320 iseasily managed by base station 310 because base station 310 is a trafficaggregation point of all connected relay stations (including relaystation 320).

Let C_(bm) 340, C_(rm) 341, and C_(br) 341, be the capacity of atransmit/receive pair of base station 310/mobile station 330, relaystation 320/mobile station 330, and base station 310/relay station 320,respectively. In one embodiment, a downlink cell boundary (i.e.,downlink to mobile station 330) between base station 310 and relaystation 320 is the position where the following equation is satisfied.

$\begin{matrix}{\frac{1}{C_{bm}} = {\frac{1}{C_{br}} + \frac{1}{C_{rm}}}} & (1)\end{matrix}$

In one embodiment, the inverse of capacity value

$\left( {{e.g.},\frac{1}{C_{bm}}} \right)$

is the 1-bit transmission time of a connection. For example,

$\frac{1}{C_{bm}}$

represents 1-bit transmission time of the connection between basestation 310 and mobile station 330. In one embodiment, the 1-bittransmission time of a direct connection

$\left( \frac{1}{C_{bm}} \right)$

and 1-bit transmission time of a connection going through relay station

$320\left( {\frac{1}{C_{br}} + \frac{1}{C_{rm}}} \right)$

are approximately equal at the cell boundary.

Similarly, in determining an uplink cell boundary (i.e. uplink frommobile station 330) between base station 310 and relay station 320, letC_(mb), C_(mr), and C_(rb) be the capacity for a transmit/receive pairof mobile station 330/base station 320, mobile station 330/relay station320, and relay station 320/base station 310, respectively. In oneembodiment, a cell boundary for the uplink transmission (from mobilestation 330) is a position where the following equation is satisfied:

$\begin{matrix}{\frac{1}{C_{mb}} = {\frac{1}{C_{mr}} + \frac{1}{C_{rb}}}} & (2)\end{matrix}$

In one embodiment, base station 310 and relay station 330 are shared bymultiple users. Equation (1) and equation (2) are modified to includeload of each base station to improve temporally-fair scheduling. In thefollowing equations, E(x) represents the expected value (average or min)of a sample. N^(d) _(b) represents a number of mobile stationsassociated with base station 310 for a downlink transmission, whereasN^(d) _(r) represents a number of mobile stations associated with relaystation 320 for a downlink transmission. N^(u) _(b) represents a numberof mobile stations associated with base station 310 for an uplinktransmission, whereas N^(u) _(r) represents a number of mobile stationsassociated with relay station 320 for an uplink transmission.

In one embodiment, a cell boundary for the downlink transmission (tomobile station 330) is a position where the following equation issatisfied:

$\begin{matrix}{\frac{E\left\lbrack {N_{b}^{d} + 1} \right\rbrack}{C_{bm}} = {\frac{E\left\lbrack {N_{r}^{d} + 1} \right\rbrack}{C_{br}} + \frac{E\left\lbrack {N_{r}^{d} + 1} \right\rbrack}{C_{rm}}}} & (3)\end{matrix}$

In one embodiment, a cell boundary for the uplink transmission is aposition where the following equation is satisfied:

$\begin{matrix}{\frac{E\left\lbrack {N_{b}^{u} + 1} \right\rbrack}{C_{mb}} = {\frac{E\left\lbrack {N_{r}^{u} + 1} \right\rbrack}{C_{rb}} + \frac{E\left\lbrack {N_{r}^{u} + 1} \right\rbrack}{C_{mr}}}} & (4)\end{matrix}$

In one embodiment, if N active mobile stations share a base station, theeffective transmission time of a user increases by approximately N timesbecause that user only uses 1/N fractional time. In one embodiment,(N+1) is used in equation (3) and (4) instead of N to reflect that thismobile station is a potential additional mobile station which is goingto join the network.

Control and Signaling

In one embodiment, uplink and downlink communications are not fullyindependent of each other. For example, a mobile station is required torequest for transmission slots from a base station (before sending datavia an uplink transmission) in a cellular network. In one embodiment, abase station grants transmission slots by transmitting schedulinginformation to the mobile station via a downlink control channel. In oneembodiment, if hybrid automatic repeat request (HARQ) is enabled, datatransmission requires acknowledgement to be sent immediately to theopposite direction. Thus, good connectivity between neighboring basestations is important even if uplink/downlink base stations are twodifferent base stations.

In one embodiment, efficient backbone communications (backhaulcommunication) among base stations is performed together with otheradvanced radio technologies, such as, for example, collaborativemulti-point MIMO (multiple-input multiple-output) systems.

In one embodiment, transmission (e.g., in the downlink direction)regarding scheduling information for an uplink transmission is referredto herein as uplink control. In one embodiment, transmission regardingscheduling information for a downlink transmission is referred to hereinas downlink control.

In one embodiment, all other transmission of control data via an uplinkis referred to herein as uplink signaling. In one embodiment, uplinksignaling includes, but is not limited to, ranging, HARQ feedback fordownlink data, sounding, and channel quality indicator (CQI) channelfeedback. In one embodiment, all other transmission of control data viaa downlink is referred to herein as downlink signaling. In oneembodiment, downlink signaling includes, but is not limited, systemconfiguration broadcast and HARQ feedback for uplink data.

FIG. 4 a shows an embodiment of a system communicating control/signalingdata without using a backbone connection between two base stations.Referring to FIG. 4 a, in one embodiment, the communication systemcomprises base station 410 base station 412, mobile station 411, andseveral links. In one embodiment, base station 412 is a base station. Inone embodiment, mobile station 411 uses base station 410 as an uplinkbase station and uses base station 412 as a downlink base station.

In one embodiment, mobile station 411 maintains at least four links (twodata links and two signaling links) with two base stations (i.e., basestations 410-411). Each signaling link is associated with acorresponding data link in a reverse direction.

In one embodiment, thin downlink signaling 432 and uplink control 431data flows in a direction from base station 410 to mobile station 411.Uplink data 430 data flow in a direction from mobile station 411 towardsbase station 410. In one embodiment, thin uplink signaling 442 dataflows in a direction from mobile station 411 towards base station 412.Downlink data 441 and downlink control 440 data flow in a direction frombase station 412 to mobile station 411.

In one embodiment, without a backbone connection, control/signaling dataare transmitted without going through a relay station or a centralizedsystem. In one embodiment, coordination is required to prevent multiplelinks (e.g., from mobile station 411 to base station 410) occurconcurrently, because mobile station 411 operates at low transmit powerand the uplink capacity is limited by the low transmit power.

FIG. 4 b is an embodiment of a system communicating control data withthe use of a backbone connection. Referring to FIG. 4 b, in oneembodiment, the communication system comprises base station 480, basestation 482, mobile station 481, and several links. In one embodiment,base station 482 is a base station. In one embodiment, mobile station481 uses base station 480 as an uplink base station and uses basestation 482 as a downlink base station.

In one embodiment, mobile station 411 maintains at least two links and abackbone link (wired or wireless). Each link transmits data, signaling,control data, or any combination thereof.

In one embodiment, uplink signaling 460 and uplink data 461 share a linkand the data flow in a direction from mobile station 481 to base station480. In one embodiment, thin uplink control 472, downlink data 471,downlink control and signaling 470 share a link and the data flow in adirection from base station 482 to mobile station 411.

In one embodiment, in addition to the two links, there is a backboneconnection 450 established from base station 480 to base station 482. Inone embodiment, uplink control/signaling is transferred from uplink basestation (i.e., base station 481) to downlink base station (i.e., basestation 482) via backbone 450, which then transmits to mobile station481 with a small penalty on latency. In one embodiment, backbone 450 isused to copy uplink signaling (452) and to transfer uplink controlrequest (453), from base station 480 to base station 482.

In one embodiment, data that are timing critical (e.g., HARQ feedback)are more suitable to be transmitted using a communication system withrespect to FIG. 4 a. In one embodiment, data that are less timingcritical (e.g., uplink scheduling information, CQI feedback, and uplinkranging) are transmitted using a communication system with respect toeither FIG. 4 a or FIG. 4 b. In one embodiment, uplink schedulinginformation is managed at a base station or is coordinated amongmultiple base stations.

FIG. 5 is a flow diagram of one embodiment of a process to determine abase station for sending data (uplink transmission) and a base stationfor receiving data (downlink transmission). The process is performed byprocessing logic that may comprise hardware (circuitry, dedicated logic,etc.), software (such as one that is run on a general purpose computersystem or a dedicated machine), or a combination of both. In oneembodiment, the process is performed in conjunction with a networkapparatus (e.g., network apparatus with respect to FIG. 2). In oneembodiment, the process is performed by a computer system such as thecomputer system shown in FIG. 7.

Referring to FIG. 5, in one embodiment, processing logic begins bydetermining network parameters, such as, for example, load associatedwith a base station, distance associated with each base station,capacity of an connection (especially downlink capacity), and a SINRvalue associated with an connection (process block 500).

In one embodiment, processing logic selects base stations (a first basestation and a second base station) based on two criteria related withthe network parameters. In one embodiment, a first criterion is based ona value indicative of maximum SINR (maxSINR) of signal received.Processing logic determines a second criterion based on the minimumtransmit power for an uplink transmission of a network device. In oneembodiment, processing logic selects a downlink transmission based onthe first criterion and selects an uplink transmission based on thesecond criterion (process block 510)

In one embodiment, processing logic establishes an uplink transmissionand a downlink transmission with a first base station and a second basestation respectively. In one embodiment, processing logic transmits andreceives data via the uplink and downlink transmissions (process block520).

FIG. 6 is a diagram representation of a wireless communication system inaccordance with one embodiment of the invention. Referring to FIG. 6, inone embodiment, wireless communication system 900 includes one or morewireless communication networks, generally shown as 910, 920, and 930.

In one embodiment, the wireless communication system 900 includes awireless personal area network (WPAN) 910, a wireless local area network(WLAN) 920, and a wireless metropolitan area network (WMAN) 930. Inother embodiments, wireless communication system 900 includes additionalor fewer wireless communication networks. For example, wirelesscommunication network 900 includes additional WPANs, WLANs, and/orWMANs. The methods and apparatus described herein are not limited inthis regard.

In one embodiment, wireless communication system 900 includes one ormore subscriber stations (e.g., shown as 940, 942, 944, 946, and 948).For example, the subscriber stations 940, 942, 944, 946, and 948 includewireless electronic devices such as, for example, a desktop computer, alaptop computer, a handheld computer, a tablet computer, a cellulartelephone, a pager, an audio/video player (e.g., an MP3 player or a DVDplayer), a gaming device, a video camera, a digital camera, a navigationdevice (e.g., a GPS device), a wireless peripheral (e.g., a printer, ascanner, a headset, a keyboard, a mouse, etc.), a medical device (e.g.,a heart rate monitor, a blood pressure monitor, etc.), and othersuitable fixed, portable, or mobile electronic devices. In oneembodiment, wireless communication system 900 includes more or fewersubscriber stations.

In one embodiment, subscriber stations 940, 942, 944, 946, and 948 use avariety of modulation techniques such as spread spectrum modulation(e.g., direct sequence code division multiple access (DS-CDMA),frequency hopping code division multiple access (FH-CDMA), or both),time-division multiplexing (TDM) modulation, frequency-divisionmultiplexing (FDM) modulation, orthogonal frequency-divisionmultiplexing (OFDM) modulation, multi-carrier modulation (MCM), othersuitable modulation techniques, or combinations thereof to communicatevia wireless links.

In one embodiment, laptop computer 940 operates in accordance withsuitable wireless communication protocols that require very low power,such as, for example, Bluetooth™, ultra-wide band (UWB), radio frequencyidentification (RFID), or combinations thereof to implement the WPAN910. In one embodiment, laptop computer 940 communicates with devicesassociated with the WPAN 910, such as, for example, video camera 942,printer 944, or both via wireless links.

In one embodiment, laptop computer 940 uses direct sequence spreadspectrum (DSSS) modulation, frequency hopping spread spectrum (FHSS)modulation, or both to implement the WLAN 920 (e.g., a basic service set(BSS) network in accordance with the 802.11 family of standardsdeveloped by the Institute of Electrical and Electronic Engineers (IEEE)or variations and evolutions of these standards). For example, laptopcomputer 940 communicates with devices associated with the WLAN 920 suchas printer 944, handheld computer 946, smart phone 948, or combinationsthereof via wireless links.

In one embodiment, laptop computer 940 also communicates with accesspoint (AP) 950 via a wireless link. AP 950 is operatively coupled torouter 952 as described in further detail below. Alternatively, AP 950and router 952 may be integrated into a single device (e.g., a wirelessrouter).

In one embodiment, laptop computer 940 uses OFDM modulation to transmitlarge amounts of digital data by splitting a radio frequency signal intomultiple small sub-signals, which in turn, are transmittedsimultaneously at different frequencies. In one embodiment, laptopcomputer 940 uses OFDM modulation to implement WMAN 930. For example,laptop computer 940 operates in accordance with the 802.16 family ofstandards developed by IEEE to provide for fixed, portable, mobilebroadband wireless access (BWA) networks (e.g., the IEEE std. 802.16,published 2004), or combinations thereof to communicate with basestations, shown as 960, 962, and 964, via wireless link(s).

Although some of the above examples are described above with respect tostandards developed by IEEE, the methods and apparatus disclosed hereinare readily applicable to many specifications, standards developed byother special interest groups, standard development organizations (e.g.,Wireless Fidelity (Wi-Fi) Alliance, Worldwide Interoperability forMicrowave Access (WiMAX) Forum, Infrared Data Association (IrDA), ThirdGeneration Partnership Project (3GPP), etc.), or combinations thereof.The methods and apparatus described herein are not limited in thisregard.

WLAN 920 and WMAN 930 are operatively coupled to network 970 (public orprivate), such as, for example, the Internet, a telephone network (e.g.,public switched telephone network (PSTN)), a local area network (LAN), acable network, and another wireless network via connection to anEthernet, a digital subscriber line (DSL), a telephone line, a coaxialcable, any wireless connection, etc., or combinations thereof.

In one embodiment, WLAN 920 is operatively coupled to network 970 via AP950 and router 952. In another embodiment, WMAN 930 is operativelycoupled to network 970 via base station(s) 960, 962, 964, orcombinations thereof. Network 970 includes one or more network servers(not shown).

In one embodiment, wireless communication system 900 includes othersuitable wireless communication networks, such as, for example, wirelessmesh networks, shown as 980. In one embodiment, AP 950, base stations960, 962, and 964 are associated with one or more wireless meshnetworks. In one embodiment, AP 950 communicates with or operates as oneof mesh points (MPs) 990 of wireless mesh network 980. In oneembodiment, AP 950 receives and transmits data in connection with one ormore of MPs 990. In one embodiment, MPs 990 include access points,redistribution points, end points, other suitable connection points, orcombinations thereof for traffic flows via mesh paths. MPs 990 use anymodulation techniques, wireless communication protocols, wiredinterfaces, or combinations thereof described above to communicate.

In one embodiment, wireless communication system 900 includes a wirelesswide area network (WWAN) such as a cellular radio network (not shown).Laptop computer 940 operates in accordance with other wirelesscommunication protocols to support a WWAN. In one embodiment, thesewireless communication protocols are based on analog, digital, ordual-mode communication system technologies, such as, for example,Global System for Mobile Communications (GSM) technology, Wideband CodeDivision Multiple Access (WCDMA) technology, General Packet RadioServices (GPRS) technology, Enhanced Data GSM Environment (EDGE)technology, Universal Mobile Telecommunications System (UMTS)technology, High-Speed Downlink Packet Access (HSDPA) technology,High-Speed Uplink Packet Access (HSUPA) technology, other suitablegeneration of wireless access technologies (e.g., 3G, 4G, etc.)standards based on these technologies, variations and evolutions ofthese standards, and other suitable wireless communication standards.Although FIG. 6 depicts a WPAN, a WLAN, and a WMAN, In one embodiment,wireless communication system 900 includes other combinations of WPANs,WLANs, WMANs, and WWANs. The methods and apparatus described herein arenot limited in this regard.

In one embodiment, wireless communication system 900 includes otherWPAN, WLAN, WMAN, or WWAN devices (not shown) such as, for example,network interface devices and peripherals (e.g., network interface cards(NICs)), access points (APs), redistribution points, end points,gateways, bridges, hubs, etc. to implement a cellular telephone system,a satellite system, a personal communication system (PCS), a two-wayradio system, a one-way pager system, a two-way pager system, a personalcomputer (PC) system, a personal data assistant (PDA) system, a personalcomputing accessory (PCA) system, other suitable communication system,or combinations thereof.

In one embodiment, subscriber stations (e.g., 940, 942, 944, 946, and948) AP 950, or base stations (e.g., 960, 962, and 964) includes aserial interface, a parallel interface, a small computer systeminterface (SCSI), an Ethernet interface, a universal serial bus (USB)interface, a high performance serial bus interface (e.g., IEEE 1394interface), any other suitable type of wired interface, or combinationsthereof to communicate via wired links. Although certain examples havebeen described above, the scope of coverage of this disclosure is notlimited thereto.

Embodiments of the invention may be implemented in a variety ofelectronic devices and logic circuits. Furthermore, devices or circuitsthat include embodiments of the invention may be included within avariety of computer systems. Embodiments of the invention may also beincluded in other computer system topologies and architectures.

FIG. 7 illustrates an example of a computer system in conjunction withone embodiment of the invention. Processor 705 accesses data from level1 (L1) cache memory 706, level 2 (L2) cache memory 710, and main memory715. In other embodiments of the invention, cache memory 706 may be amulti-level cache memory comprise of an L1 cache together with othermemory such as an L2 cache within a computer system memory hierarchy andcache memory 710 are the subsequent lower level cache memory such as anL3 cache or more multi-level cache. Furthermore, in other embodiments,the computer system may have cache memory 710 as a shared cache for morethan one processor core.

In one embodiment, memory/graphic controller 716, IO controller 717, orcombinations thereof is integrated in processor 705. In one embodiment,parts of memory/graphic controller 716, parts of IO controller 717, orcombinations thereof is integrated in processor 705.

Processor 705 may have any number of processing cores. Other embodimentsof the invention, however, may be implemented within other deviceswithin the system or distributed throughout the system in hardware,software, or some combination thereof.

Main memory 715 may be implemented in various memory sources, such asdynamic random-access memory (DRAM), hard disk drive (HDD) 720, solidstate disk 725 based on NVRAM technology, or a memory source locatedremotely from the computer system via network interface 730 or viawireless interface 740 containing various storage devices andtechnologies. The cache memory may be located either within theprocessor or in close proximity to the processor, such as on theprocessor's local bus 707. Furthermore, the cache memory may containrelatively fast memory cells, such as a six-transistor (6T) cell, orother memory cell of approximately equal or faster access speed.

Other embodiments of the invention, however, may exist in othercircuits, logic units, or devices within the system of FIG. 7.Furthermore, in other embodiments of the invention may be distributedthroughout several circuits, logic units, or devices illustrated in FIG.7.

The invention is not limited to the embodiments described, but can bepracticed with modification and alteration within the spirit and scopeof the appended claims. For example, it should be appreciated that thepresent invention is applicable for use with all types of semiconductorintegrated circuit (“IC”) chips. Examples of these IC chips include butare not limited to processors, controllers, chipset components,programmable logic arrays (PLA), memory chips, network chips, or thelike. Moreover, it should be appreciated that exemplarysizes/models/values/ranges may have been given, although embodiments ofthe present invention are not limited to the same. As manufacturingtechniques (e.g., photolithography) mature over time, it is expectedthat devices of smaller size could be manufactured.

Whereas many alterations and modifications of the embodiment of thepresent invention will no doubt become apparent to a person of ordinaryskill in the art after having read the foregoing description, it is tobe understood that any particular embodiment shown and described by wayof illustration is in no way intended to be considered limiting.Therefore, references to details of various embodiments are not intendedto limit the scope of the claims which in themselves recite only thosefeatures regarded as essential to the invention.

1-21. (canceled)
 22. A method to connect with two Evolved Node B (eNB)stations simultaneously, comprising: associating with a first eNB toreceive downlink transmissions from the first eNB except to onlytransmit control data to the first eNB; and associating with a secondeNB for uplink transmissions to the second eNB except to only receivecontrol data from the second eNB.
 23. The method as claimed in claim 22,further comprising: receiving automatic repeat request (ARQ)transmissions over the downlink from the first eNB and transmitting anacknowledgment to the first eNB as the control data in response toreceived ARQ transmissions; and sending ARQ transmissions over theuplink to the second eNB and receiving an acknowledgment from the secondeNB as the control data in response to the sent ARQ transmissions. 24.The method as claimed in claim 23, wherein the ARQ transmissionscomprise hybrid automatic repeat request (HARQ) transmissions.
 25. Auser equipment to connect with two Evolved Node B (eNB) stationssimultaneously, comprising: a controller to associate with a first eNBfor downlink transmissions, and to associate with a second eNB foruplink transmissions; and a transceiver to receive downlinktransmissions from the first eNB except to only transmit control data tothe eNB, and to transmit uplink transmissions to the second eNB exceptto receive control data from the second eNB.
 26. The user equipment asclaimed in claim 25, wherein the transceiver is configured to receiveautomatic repeat request (ARQ) transmissions over the downlink from thefirst eNB and to transmit an acknowledgment to the first eNB as thecontrol data in response to received ARQ transmissions, and to send ARQtransmissions over the uplink to the second eNB and to receive anacknowledgment from the second eNB as the control data in response tothe sent ARQ transmissions.
 27. The user equipment as claimed in claim26, wherein the ARQ transmissions comprise hybrid automatic repeatrequest (HARQ) transmissions.
 28. A non-transitory medium havinginstructions stored thereon that, if executed, result in connecting withtwo Evolved Node B (eNB) stations simultaneously, by: associating with afirst eNB to receive downlink transmissions from the first eNB except toonly transmit control data to the first eNB; and associating with asecond eNB for uplink transmissions to the second eNB except to onlyreceive control data from the second eNB.
 29. The non-transitory mediumas claimed in claim 28, wherein the instructions, if executed furtherresult connecting with two Evolved Node B (eNB) stations simultaneouslyby: receiving automatic repeat request (ARQ) transmissions over thedownlink from the first eNB and transmitting an acknowledgment to thefirst eNB as the control data in response to received ARQ transmissions;and sending ARQ transmissions over the uplink to the second eNB andreceiving an acknowledgment from the second eNB as the control data inresponse to the sent ARQ transmissions.
 30. The non-transitory medium asclaimed in claim 29, wherein the ARQ transmissions comprise hybridautomatic repeat request (HARQ) transmissions.
 31. A method to connectwith two Evolved Node B (eNB) stations simultaneously, comprising:determining a first eNB to transmit data over an uplink channel;determining a second eNB to receive data over a downlink channel;transmitting data to the first eNB over the uplink channel without beingassociated with the first eNB for the downlink channel; and receivingdata from the second eNB over the downlink channel without beingassociated with the second eNB for the uplink channel.
 32. The method ofclaim 31, further comprising: establishing a first link, with a lowerbandwidth than the uplink channel, to receive only first network controldata from the first eNB; and establishing a second link, with a lowerbandwidth than the downlink channel, to transmit only second networkcontrol data to the second eNB.
 33. The method as claimed in claim 31,further comprising: receiving automatic repeat request (ARQ)transmissions over the downlink from the first eNB and transmitting anacknowledgment to the first eNB as the control data in response toreceived ARQ transmissions; and sending ARQ transmissions over theuplink to the second eNB and receiving an acknowledgment from the secondeNB as the control data in response to the sent ARQ transmissions. 34.The method as claimed in claim 33, wherein the ARQ transmissionscomprise hybrid automatic repeat request (HARQ) transmissions.
 35. Auser equipment to connect with two Evolved Node B (eNB) stationssimultaneously, comprising: a control to determine a first eNB totransmit data over an uplink channel, and to determine a second eNB toreceive data over a downlink channel; and a transceiver to transmit datato the first eNB over the uplink channel without being associated withthe first eNB for the downlink channel, and to receive data from thesecond eNB over the downlink channel without being associated with thesecond eNB for the uplink channel.
 36. The user equipment of claim 35,wherein the transceiver is configured to establish a first link, with alower bandwidth than the uplink channel, to receive only first networkcontrol data from the first eNB, and to establish a second link, with alower bandwidth than the downlink channel, to transmit only secondnetwork control data to the second eNB.
 37. The user equipment asclaimed in claim 35, wherein the transceiver is configured to receiveautomatic repeat request (ARQ) transmissions over the downlink from thefirst eNB and transmitting an acknowledgment to the first eNB as thecontrol data in response to received ARQ transmissions, and to send ARQtransmissions over the uplink to the second eNB and receiving anacknowledgment from the second eNB as the control data in response tothe sent ARQ transmissions.
 38. The user equipment as claimed in claim37, wherein the ARQ transmissions comprise hybrid automatic repeatrequest (HARQ) transmissions.
 39. A non-transitory medium comprisinginstructions stored thereon that, if executed, result in connecting withtwo Evolved Node B (eNB) stations simultaneously, by: determining afirst eNB to transmit data over an uplink channel; determining a secondeNB to receive data over a downlink channel; transmitting data to thefirst eNB over the uplink channel without being associated with thefirst eNB for the downlink channel; and receiving data from the secondeNB over the downlink channel without being associated with the secondeNB for the uplink channel.
 40. The non-transitory medium of claim 39,wherein the instructions, if executed further result in connecting withtwo Evolved Node B (eNB) stations simultaneously by: establishing afirst link, with a lower bandwidth than the uplink channel, to receiveonly first network control data from the first eNB; and establishing asecond link, with a lower bandwidth than the downlink channel, totransmit only second network control data to the second eNB.
 41. Thenon-transitory medium as claimed in claim 39, wherein the instructions,if executed further result in connecting with two Evolved Node B (eNB)stations simultaneously by: receiving automatic repeat request (ARQ)transmissions over the downlink from the first eNB and transmitting anacknowledgment to the first eNB as the control data in response toreceived ARQ transmissions; and sending ARQ transmissions over theuplink to the second eNB and receiving an acknowledgment from the secondeNB as the control data in response to the sent ARQ transmissions. 42.The non-transitory medium as claimed in claim 41, wherein the ARQtransmissions comprise hybrid automatic repeat request (HARQ)transmissions.